A fortification is a military construction or building designed for the defence of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin fortis ("strong") and facere ("to make"). Roman forts and hill forts were the main antecedents of castles in Europe, which emerged in the 9th century in the Carolingian Empire. The Early Middle Ages saw the creation of some towns built around castles.